The Path to Paradise begins in Hell
by loosingletters
Summary: In one world Samael and Lucifer were at each others' throats. In this one, Lucifer is old and tired and just wants to be able to breathe. And when Samael presents him with two children, calling them solutions, Lucifer isn't quite sure if his brother knows what raising children entails. Or that one AU in which all demon kings can more or less stand each other and raise the twins.
1. Lucifer

**So, actually, I had planned to write a fun AU with is 90% bad jokes and 10% Lucifer drinking coffee.**  
 **Somehow it got a little darker.**  
 **Anyway, I hope you enjoy this story!**

Sometimes he felt far too old for this world. He'd watched kingdoms rise and fall; he had dedicated his precious, always scarce time to so many different causes, each of them promising him to cure his aching bones, his sore joints, his collapsing lungs, his raw skin, the decaying of his being.

And every ten years still he drowned in his own blood and woke up in a body foreign to him for at least another year until the suffering would start again and the familiar pain would return.

Lucifer was tired of living but even sicker of dying.

Perhaps that was the reason he had agreed to Samael's offer so easily, not even caring to negotiate the details with him, certainly a dangerous mistake to make when dealing with the King of Time. But Lucifer wanted to be able to take a breath without starting to cough and eat real meals without vomiting.

If he had given this project of Samael more consideration, maybe this situation could have been avoided.

"Their names are Rin and Yukio," Samael said, for once abandoning his foolish demeanor and acting like life was more than a simple game of chess whose outcome he'd predicted before it even started.

Lucifer studied the newborns lying innocently in their crib. If he were younger, say Astaroth's age, he wouldn't believe them to be anything but two human children with pink skin and black hair. Sleeping together like this, curled around each other, they appeared to be far from the tragedy they were sure to become.

"They're not human. What are they?"

He didn't take his eyes of them, wondering why it was so hard to tear himself away from their sight. He wasn't waiting for chaos to come crawling out of the corners, though the chance of that happening was rather high considering they were standing within Samael's home, but still there was a pull drawing him to the twins.

"I don't know," Samael admitted, frowning. "They are from Gehenna but not off Gehenna, not in the way we are."

Lucifer turned to his brother, wincing as his side stung him sharply with what felt like razors. His painkillers were wearing off again, he needed to take his next dose soon if he wanted to get some shut-eye.

"What are they?" He pressed.

"Children."

" _Whose_ , Samael!? Don't play games with me. Not now."

Samael's eyes flashed dangerously but even so, he just laughed drily and didn't hesitate to answer.

"Its, his, Gehenna's, Satan's or whatever name it has decided to go by now. Apparently, the Ego of a world can develop beyond the boundaries of one plain as long as its thirst for more is saturated, which it never will. Demons are never content, we're always starving. These two are 'Plan B' as far as I can tell. They contain the same power, if weaker, within them. That power is sure to grow beyond everything even my seals could control. They are basically Gehenna's failsafe if I can keep it from opening a Gate to Assiah; the perfect vessels."

That plan sounded just mad enough to hail from the world they kept trying to escape.

"We can't let that happen. Why have you allowed them to stay alive?"

Murder usually wasn't Lucifer's first choice of action but already the existence of these two innocent beings risked the safety of Assiah. It would be unwise to let them live and grow up to be Gehenna's perfect puppets.

"Because of all the possibilities these two promise. They are similar to Gehenna in all but one; they are part human. They were born in Assiah! Imagine what we could do with that, Lucifer. The cores of a world in a stable human shape. All we need is for them to grow up ready to use that power."

Samael grinned like a shark, revealing the dangerous predator hidden behind the mask of a trickster.

"What are you planning, Samael?"

"I'll put a new king on Gehenna's throne and you will teach them how to do more with that crown on their heads than to simply show it off. I know you remember the fall and the shaping of Gehenna."

Oh yes, he remembered the burning of his fingers as they dug them into the darkness of nothing in particular; shaping, creating-

"You're cruel, brother," Lucifer said and stepped closer to the crib again. He reached for the fussy twin and lifted him up, gently cradling the babe. "Ruining their lives like that."

Samael snorted. "Like you care about them beyond the possibility that they might be able to relieve you of your pain."

The child calmed down and soon his breathing was even again.

"I never said I had any moral high ground."

He returned the child to his brother and, with one last glance at the two, left the room behind, his legs feeling like they wouldn't carry his weight much longer.


	2. Samael

**I am utterly convinced that in private Mephisto is a cynical little shit. Fight me.**

Samael was entirely unimpressed with the two children drooling over his carpet as they intended to crawl over to their oldest brother. Lucifer, on the other hand, was positively delighted to see the children take so well to him. Of course, he denied it but the faint smiles Lucifer probably wasn't even aware of, gave him away.

"I don't think I can take another ten years of them ruining my carpet," Samael said from his comfortable armchair in the corner of the living room.

Lucifer pulled Rin, the faster, older and so far more impressive annoyance, on his lap and reached for the pacifier lying on the coffee table. As soon as Rin saw it, he tried to get a hold of it with his pudgy little arms.

"They're not even a year old, brother. Surely you must have known how much time would go into your plot?"

Lucifer really could do without the condescending tone.

Samael rolled his eyes. "I'm not a hot-blooded brat like Amaimon. I've been patient for millennia, I can wait a decade."

Lucifer smiled pointedly at him before turning his attention back to the twins, especially Yukio as he now too had reached the demon.

He knew children had to be treated with care otherwise they'd wither away, but still, Samael wondered if Lucifer wasn't raising them overly gentle and loving. Certainly the boys didn't need to be with him every hour of the day and Samael had more than enough servants in his home which could watch them. But Lucifer denied all his suggestions and became the maid himself either way. One of these days Samael would catch him dressed in sweatpants instead of the more formal wear his brother used to prefer.

"They're not Castor and Polydeuces," Samael decided to speak up again, eager to see his brother's reaction.

And there it was, the twitching of his shoulders, the holding of his breath, the glaring-

Toying with his siblings had always brought a remarkably satisfying joy to him. He wasn't even particularly mean with his taunts. They weren't hitting anywhere too deep, or at least they shouldn't.

"That was a low blow, brother," Lucifer replied. "But seeing that Rin and Yukio should go to bed now either way, we'll leave you alone. Good night."

Lucifer picked the boy up, first Yukio, then Rin, holding them with no problem at all. Ages ago he wouldn't have shied away from this confrontation. They'd been less exhausted and more hungry for blood back then.

"Sleep well," Samael told him and watched his brother disappear down the hall with the children.

Lucifer really needed to take a break from the brats; their pull on him was too strong. Perhaps he needed to check their seals again? Their allure couldn't start to show again already.

Or maybe the problem was his brother and not Samael's seals.

Sure, Lucifer had only ever fathered a few children but he had had them. But certainly he couldn't have bonded so thoroughly with them? How strange, Samael had never felt particularly attached to his hellspawns beyond their usefulness. Then again he had never taken it upon himself to raise his children. Perhaps he should speak with Ilbis. He managed to nurture himself great vessels without any emotions getting between him and his goals.

Samael frowned as he poured himself another cup of tea.

Ilbis was busy pampering his current next vessel, wasn't he? And the child was barely older than the twins, perhaps an older playmate would teach them to become more useful and put themselves to bed.

Content with himself, Samael rose from his chair and retreated to his own bedroom, but not before he nearly fell over a lego block.

 **Also! - very important - I think I should explain what I was thinking when coming up with this idea?**  
 **I thought that since Satan = Gehenna and his defining power are the blue flames, Rin and Yukio possessing the same powers should make them more than regular demons. In fact, they have the power of what shapes a whole realm. Ergo Mephisto's hoping that with their abilities they can modify Gehenna or Assiah in its core to be able to host demon kings with bodies and their egos intact.**  
 **That's basically it.**


	3. Azazel

**Lucifer continues being the twins' *cough* mom *cough* guardian and Azazel talks a lot**.

Azazel met his youngest brothers for the first time when they were five and curious. Lucifer held each boy's hand strongly and barely let them leave his side on the way towards Azazel's resting place. It was entertaining to see the eldest so emotionally comprised.

"Is that him?" Rin asked, pointing at Azazel's intangible body. "It feels like him."

The other boy's furred his brows and focused his bright blue eyes on Azazel. "It looks like him too."

Both look up to Lucifer, eagerly awaiting his confirmation and praise.

"You're right," the King of Light said. "This is our brother Azazel, King of Spirits."

The boys took a step forward, towards him, hesitating only in the last second. Their shoulders tense, visible even through their thick winter jackets. Then, as so often already in the last minutes, they turned to Lucifer again. He nodded and that was apparently all it took for the twins to storm to the remains of his vessel. They immediately began to tell him about their lives and hobbies and training. Azazel would by no means claim to be the most human of his siblings, but even he was unsettled by Rin and Yukio's stories and how little the two seemed to care about their own wellbeing.

"You're raising puppets," Azazel told Lucifer. "What will you do with them when they have served their purpose?"

He had spent more time with humans that most of his siblings. He had studied them, their behavior and mannerisms and had learned from it. As much demon blood as the twins in front of him carried, they were human at the core. It didn't take much genius to see that, just the ability to reach into the depths of a soul.

Rin and Yukio were still chatting, unaware that he had chosen to strike up a conversation with Lucifer. He thought it was kinder to leave them to their happiness than to reveal he wasn't listening to them. It wasn't like they could hear what he and Lucifer discussed. Being the King of Spirits had more advantages than surviving in Assiah without outside help.

"I don't know what Samael is planning."

Azazel bristled in anger. "You don't know? You have become careless, Lucifer."

Careless and numb. In silence he wondered where his bloodthirsty brother had gone. Where was the King of Light who marched into the room with the screams of war following him?

"I'm not supposed to care. I am to raise them and teach them what I know of Gehenna's creation so that they can fulfill their purpose."

Azazel dug his claws into his brother's mind, a sharp reminder of his usual bitter laugh.

"I forgot the boys' lives have been predestined before they were even born. Created to be our cures."

Lucifer's footing strengthened as he braced himself for the confrontation. "They weren't created for this purpose. It is simply an opportunity which has opened up with their birth."

"Oh, please," Azazel laughed. "You don't even believe that yourself. Do you really think that Samael would let the situation escape him so much that such an opportunity would simply arise? Open your eyes, brother. Our cures have been bred and cultured like Amaimon's vessel. You better keep them close or they'll drown."

With that Azazel retreated from Lucifer's mind and returned to paying his attention to Rin and Yukio. Testing Lucifer's patience any further would be like poking a sleeping bear, perhaps funny at first but dangerous all in all.

And he rather liked the two boys, they were almost too cute and reminded him a bit of his own children.

Perhaps he should visit Shirou again. It had been a few years since he had last reached into his progeny's mind.

With this Azazel slowly drifted off again, his conscious shattering once again and running away with the wind.

 **Lucifer is not as unknowing as Azazel thinks, he's just very apathetic and can't find it in himself to care.**  
 **He's tired.**  
 **And depressed probably too. I should probably tag that.**  
 **Until next time!**  
 **Leave your thoughts behind on your way out, please!**


	4. Ilbis

Ilbis prided himself on being the only demon who truly understood humans. His siblings all could bicker, pretend and make plans to take over the world by manipulating the weak flesh bags into working for them, but the fact was that Ilbis was the only one who took the time to learn how humans worked and gained an understanding for their motivations, actions and behavior.

Of course, he didn't do it because he was interested in them or liked them. After thousands of years he was fairly sure he couldn't even grow to harbor any positive emotions towards anyone or anything besides himself. No, Ilbis was too full of himself. How could he not? He was fire and fire did nothing but burn, consume and annex.

He was hungry for power and humans were so willing to give once he understood their motivations. After all, the most exceptional gift they could give him, were themselves. Their bodies, their places in Assiah. Ilbis may not burn through a body every ten years like Lucifer, but fast enough that waiting for an opportunity to get a hold of a proper vessel was a hassle.

That, above everything else, was the reason Ilbis had learned to understand humans. If he wanted a human body, and he desperately needed one, he had to know how to get humans to make him one. Over time he had assembled a few loyal and old families. He shared his wisdom, strength and influence with them, and in turn, they provided him with somebody to share his genetic material with, once it was the time for it, and grow his own vessel.

Azazel had called it barbaric, possessing his own children, having children with his own descendants. Ilbis called it efficient. He was becoming stronger with every generation; his bodies lasted longer – what more could he wish for?

Sure, not having to change vessels at hall would be the dream, but it only took one look at Samael's solutions to know that the older demons plan would never work.

"Kaito! Kaito! Play with us!" His younger brothers shouted, pulling at Ilbis' next vessel.

Kaito turned to him, silently asking for permission. Ilbis liked the boy. It was a shame he'd erase him in a decade. The King of Fire nodded and the boys ran off, but not before twins shot him glare.

Ilbis grimaced, all teeth and no fun. Give it a decade and he'd smile like that again, watching his brothers' carefully made plans fall apart.

Ilbis was a demon king. He knew humans and he knew fire.

Rin and Yukio, as much as Lucifer pampered them and prided himself on their successes and believed they'd be his cure, would be neither his salvation nor Samael's weapons.

The twins were humans given the power of Gehenna's brightest flame but it would never be enough for them. They were young still but Ilbis could see what they would grow up to be like: possessive monsters wanting to consume and being scared of every burn mark they'd leave behind.

Perhaps they would dethrone the Ego currently shaping Gehenna, but definitely only to take the palace for them. If Samael believed he was raising puppet kings, he was a fool.

Ilbis was raising a puppet himself, simply by comparing Kaito to the twins he could tell that Gehenna's next kings weren't going to be dolls. They had too much personality and pulled everyone they met into their circle.

He wouldn't be able to change into his new vessel easily if he let Kaito stay around the twins. Their magnetism was too strong.

"Kaito won't visit again," he told Lucifer later. "But I'll stick around. It'll be interesting to see the results of your experiment here."

Ilbis didn't believe in the new world Samael and Lucifer hoped to create. He only wanted to see if, in the end, Rin and Yukio would take the world down fighting against each other to proof each other's strength or if they would break apart because of their weak humanity.


	5. Egyn

**Warnings for child abuse? Rin and Yukio are faced with horrible training which is only touched upon in this chapter but will be discussed in the next so I thought I should mention it. The kids are 13 now! They grow up so fast!**

Egyn wasn't sure why they had to be the one to patch their youngest brothers back together again, but they guessed it had something to do with Rin and Yukio being absolutely terrible patients. Egyn much preferred the times when they had been working in Lucifer's labs under more comfortable conditions. The twins' antics weren't something they could just ignore or immobilize with morphine. Though, Egyn grudgingly had to admit that the later probably wouldn't work after the twins came back from Lucifer. After hours spent in what had been dubbed their _'playroom'_ , the twins were too hyped up for the needed morphine doses being anything but lethal, never mind their mental state.

Egyn would never admit it out loud of course, but the twins frightened them. They came back too synchronized, too demonic, too much like Gehenna for Egyn to be even remotely confident around them. In moments like these, their allure seemed to draw even them in, and Egyn was a demon king for crying out loud. Neither a half breed nor some week middle-class demon; they were part of the strongest, a part of Gehenna itself!

And perhaps in that laid the reason for their downfall.

"Egyn, Egyn," Rin called, drawing out the vowels like he was trying to say their name for the first time.

"Yes, Rin?" They replied, keeping their gaze down on his arm and the syringe slowly filling with blood.

"You love us, don't you?" Yukio continued for his brother. "You'll stick with us. You won't run away and leave. When we take the crown, you will be there."

"Of course I will be there," Egyn said, wisely refraining from answering the first question. Everything within them screamed that it was a trap. In fact, nothing of Yukio's statement reminded Egyn of a question. Every word he spoke was a command, a demand.

If Egyn could look at the situation with as much humor as Ilbis could, they would laugh at the twins' behavior. Samael and Lucifer were raising excellent monarchs. The two thirteen-year-olds heirs of Gehenna were precisely what you could wish future sovereigns to be, except they hadn't wanted superior beings, had they?

"You have to promise," Rin insisted and in one swift move grabbed Egyn's hand and pulled them closer.

Forced to look up from their work, Egyn's attention was immediately captured by bright blue eyes. Rin's eyes hadn't looked like Yukio's last week, Egyn was sure. He had taken after their mother, Yuri Egin, in that aspect. Egyn would have to put that in the report as well. As small and minor that discovery was compared to the other changes the twins had gone through in the past years, it was still their job to write it down.

If only they could look away.

"You're keeping that promise, right?" Yukio took over again. He was taller than Rin, and while neither child was a giant, he still towered over Egyn.

And it was in that moment, that saying yes seemed so natural and like the right course of action to take. After all, the twins would rule someday and who was Egyn to question that. Rin and Yukio would be grand, and all consuming and all giving and all Egyn had to do was give in and return-

"I-," before Egyn could reply, the door to the room opened and Yukio and Rin sat up straight, widening the distance between them and Egyn again.

"Are you done?" Lucifer asked and Egyn used the moment to close their eyes and take a deep breath.

While such human options of calming down were almost useless given their superior sense, Egyn could still feel the connection the twins had built up – and there was no questioning that they had forced it upon them. They'd have to tell Lucifer, he needed to know that their cures were getting out of control – but now also actively shatter it. Once upon a time they wouldn't have to destroy any kind of bond because there would be nothing that could have drawn them in.

"Yes, I'm done," Egyn replied and hastily collected their things.

The moment Egyn's body would be fixed, they'd leave and run as far away as they could. They couldn't wait for all of this to be over, though they wondered if such a phase would ever come or if this path they had chosen could only end in damnation.

But it wasn't like a demon who had only ever known hell could really tell what perdition was when they had never gotten a taste of heaven. Maybe they should ask Lucifer, he would know even though his judgment was clouded by the insanity of Samael's plan.

"But you didn't even draw my blood," Yukio protested.

Maybe Egyn should just punch him and die before it could all spin out of control later.

"I don't need to today. Now go, you're free for the day."

Egyn wanted them out of the room, out of their life for the next seven days until they had figured out how to deal with Rin and Yukio.

"You heard your sibling, off you go," Lucifer told them.

The two thirteen-year-old sighed and just like any other teenager walked out of the room with freaking pouts on their faces. They didn't look like monsters anymore, their faces weren't twisted impressions of Gehenna. Had Egyn just imagined it all?

Lucifer looked over Egyn's half written report, frowning for a moment before his expression took on its usual unimpressive mask.

"Egyn, we will talk tonight."

The King of Water just nodded, not letting the twins out of their eyes until they were finally gone. They were both almost out of the door again when Rin spoke up.

"Heaven's not all that different."

Ilbis was a fool, of that Egyn was sure now. They were right to be frightened of their siblings. Nothing about this situation was even remotely amusing. This was the apocalypse waiting to happen.

And there was no escape.

 **Thanks for reading!**


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